MEDIAN-EMINENCE CORTICOTROPIN-RELEASING HORMONE CONTENT FOLLOWING PRENATAL STRESS AND NEONATAL HANDLING

Neonatal handling produces enduring changes in hypothalamic-pituitary- adrenal (HPA) axis activation in response to acute stress presentation . Handled rats display reduced HPA activity in response to stress, whi ch is associated with increased hippocampal glucocorticoid receptor de nsities and decreased median eminence corticotrophin-releasing hormone (CRH) content. Prenatal stress (PS) also has long-term consequences o n HPA responsivity to stress and related behavioral profiles. On the b asis of earlier behavioral data suggesting that PS contributed to the expression of handled responses, we investigated how PS and handling m ight interact to affect median eminence CRH content. Groups of prenata lly stressed rats and controls were subjected to a handling procedure or left undisturbed. Adult rats were killed and median eminence CRH le vels were assayed as well as plasma corticosterone (CORT), PS and hand ling did not affect CRH content; however, handled plus PS rats exhibit ed significantly reduced CRH levels. Handling decreased plasma CORT co ncentrations, an effect that was absent in the PS rats. We contend tha t PS can modulate an animal's sensitivity to later environmental manip ulations while producing minimal effects on its own. Researchers inter ested in early environmental conditions and later physiologic and beha vioral responses should monitor their subjects' gestational history.